“In terms of numbers, the greatest pandemic in human history is AIDS,” Dr. Robert Gallo said to a full house at the MacLeod Auditorium on Thursday afternoon. “There are now 25 million people who have died of AIDS, and approximately 50 million who are now infected.” As he went on to talk about his work in AIDS research, he admitted, “You can’t do this full-time, you can’t survive.”

Gallo, who is Director and Professor at the Institute of Human Virology in Baltimore, was a Gairdner Award recipient in 1987. He is best known for his discovery of the Human Immunodeficiency Virus, HIV. He also pioneered the development of the HIV blood test in the early 1980s, enabling health care workers for the first time to screen for the HIV virus. This led to more rapid diagnosis, while simultaneously protecting patients receiving blood transfusions from contracting the disease. As a diagnostic tool, Gallo calls the blood test “simple and safe to work with.”

Before, diagnosing the disease posed a unique challenge. There were two basic phenomena that made diagnosis particularly difficult for this disease. When epidemiologists found cases of AIDS in the early 1980s, patients were asked questions like “What did you do last week?” or “What did you do last month?” Doctors did not ask patients what they did ten years ago, even though the disease has a relatively long latency period. The second problem was that by the time the disease became apparent, the person already had a large number of other microbial infections. It was therefore not possible to pinpoint the causative agent.

To eradicate HIV and really cure the disease, Gallo says, there has to be a new technology that can identify sequences in DNA of the [infected] cell and specifically kill that cell. HIV is a retrovirus, with RNA as its genetic material. When the virus enters a human cell of the immune system, its RNA makes a DNA complement of itself. This DNA is then inserted, or “hidden,” into the genetic sequence of the host cell. All subsequent replication of the cell’s genetic material will contain the viral genes.

Gallo recalled instances of false optimism in the past. “Many times, researchers thought that they had eradicated HIV, only to find that there are cells that are very, very, long lived that harbour complete viruses capable of being activated.”

As we progress into the new millennium, however, there are good reasons to be optimistic about future AIDS research. The way HIV enters cells in the immune system is now much better understood than it was in the early 1990s. As Gallo says, “This advance gives us good ideas about how to block HIV entry, from the therapeutic point of view as well as from the point of view of preventive vaccine.”

In addition, there is an increasing level of friendship, cooperation and trust between people from both developing and developed nations. “We have a major collaboration with Nigeria. It’s unbelievable. This would’ve been impossible ten years ago,” said Gallo. In addition, the U.S. government and private foundations are allocating more money to vaccine development.

Finally, Gallo and his colleagues are working on developing vaccine candidates that can cover all the variants of HIV. The variants of HIV are almost endless, named A, B, C, D, and so on. The major one in the world is C. In industrialized nations such as Canada, U.S., Australia and various countries in Europe, the primary variant is B. “Laboratory tests with monkeys show that we can block a wide range of HIV variants,” Gallo says.